Heat-exchanger

ABSTRACT

A heat exchanger comprising a plurality of parallel passages for a first fluid, each of said passages containing a packing, and, in alternation with said passages, groups of parallel shapes. Each of said shapes is provided with a longitudinal channel for the circulation of a second fluid and has two opposed faces respectively adjacent to two successive passages disposed on each side of the corresponding group of shapes, the shapes of a same group limiting between them spaces for the collection and the detection of possible leakage.

United States Patent Inventors Raymond Isaaz Naymont-Uzemain; Georges Vailhen, Epinal, France Appl. No. 791,691 Filed Jan. 16, 1969 Patented Mar. 16, 1971 Assignee Societe Trane Epinal, France Priority Feb. 5, 1968 France 138,754

HEAT-EXCHANGER 2 Claims, 6 Drawing Figs.

U.S. Cl 165/166, 165/70 Int. Cl F28g 3/00 Field of Search 165/70 Primary ExaminerMartin P. Schwadron Assistant ExaminerThe0phil W. Streule Attorney-Cameron, Kerkam and Sutton ABSTRACT: A heat exchanger comprising a plurality of parallel passages for a first fluid, each of said passages containing a packing, and, in alternation with said passages, groups of parallel shapes. Each of said shapes is provided with a longitudinal channel for the circulation of a second fluid and has two opposed faces respectively adjacent to two successive passages disposed on each side of the corresponding group of shapes, the shapes of a same group limiting between them spaces for the collection and the detection of possible leakage.

Patented March 16, 1971 I 3,570,593

4 Sheets-Sheet 1 Patented March 16, 1971 4 Sheets-Sheet 5 FIG. 4

Patented March 16,1971 I 3,570,593

4 Sheets-Sheet 4 HEAT-EXCHANGER The present invention is relating to a heat-exchanger of the type comprising a plurality of parallel passages, each of them containing a packing made in particular of a corrugated sheet.

Such exchangers, often called compact exchangers, are known wherein said passages are limited by parallel separating plates and wherein the successive passages are alternatively connected to two circuits conducting two exchange fluids, respectively. In the more usual. embodiment, the various passages are assembled by brazing the packings on the adjacent separating plates. The packing is, for example, a periodically deformed sheet alternatively into contact with each of the two separating plates adjacent the corresponding passage, said sheet being brazed on said plates at the level of the points of contact.

The heat-exchange between the two fluids is thus made through the separating plates and the packings form an additional exchange-surface for the fluid to which they are exposed.

The invention aims essentially at keeping the advantages of said kind of exchangers, particularly their compactness and the very good efficiency of the exchange, while allowing to increase the safety in operation if they are designed for an exchange between two fluids that have to be prevented from being into contact, for example if said fluids can give rise to a really dangerous reaction if they are brought in presence of one another. To this end, the invention aims at increasing the importance of the number of the barriers separating the circuits of the two fluids without affecting the exchange, or, for the least, at more easily detecting the possible leakages from one or the other of the circuits.

The invention relates to an exchanger comprising a plurality of parallel passages for a first fluid, each of said passages containing a packing made in particular of a corrugated sheet, said exchanger being essentially characterized in that it comprises, in alternation with said passages, groups of parallel shapes, each of said shapes being provided with a longitudinal channel for the circulation of a second fluid and having two opposed faces respectively adjacent to the two successive passages disposed on each side of the corresponding group of shapes, the shapes of a same group limiting between them collecting spaces for detecting the possible leakages.

The exchanger according to the invention is particularly convenient if the first fluid is a gaseous one and the second fluid, a liquid one. As a matter of fact, it allows to adapt at best the relation between the exchange surfaces respectively in contact with each of the two fluids, with respect to the relative exchange factors of said fluids.

According to a preferred embodiment of the invention, every passage for the first fluid is limited by two parallel plates, both in thermal contact with the packing of the passage and the adjacent shapes.

According to a particularly advantageous embodiment of the invention, the shapes contain pipes within the channels for the circulation of the second fluid.

The exchanger according to the invention comprises, preferably but not necessarily, both such plates and such pipes that form two additional barriers, added to the barrier formed by the shapes, between the circuits of the two fluids materialized the one, by the passages between the plates, the other, by the pipes within the shapes. Said barriers prevent any contact between the two fluids with a practically total safety.

In a particularly advantageous embodiment, the shapes, the packings and the separating plates, occasionally mounted, limiting the passages for the first fluid, aremade of aluminum and interconnected by brazing them with a silicon-aluminium alloy, for example. While ensuring the cohesion of the assembly, the brazed connections make for the heat conduction between the various elements.

Pipes made of a material different from the one of the shape can be disposed within said shapes. The connection between the pipes and the shapes can be made by expanding the pipes for example. The use of said pipes allows to choose the materi' als with respect of the particular properties of every fluid. Thus, if the shapes are made of aluminum the pipes can be made of any other metal or alloy so that said pipes can conduct a second fluid liable to attack aluminum.

Various embodiments of the invention will be now described by way of a nonlimitative example, wherein the heat-exchanger is more particularly designed for a heat exchange between a first gaseous fluid and a second liquid fluid, said fluids being liable to react dangerously one with another: for example uranium hexafluoride and water. However, the exchanger according to the invention can be used advantageously for other applications, for example in cryogeny, if one of the exchange fluids is used under a high pressure.

The description refers to the drawings wherein:

FIG. I is an exploded view of a first embodiment of the exchanger according to the invention wherein said exchanger has a parallelepipedic shape;

FIG. 2 shows another embodiment wherein the exchanger is limited by a cylindrical volume;

FIG. 3 is another embodiment of the exchanger shown in the FIG. 1, wherein the plane plates limiting the passages for the first exchange fluid are suppressed;

FIG. 4 shows other embodiments for the passages of the first fluid, for the shapes and for the conducting pipes of the second fluid;

FIGS. 5 and 6 are schematic views, given by way of example, of two embodiments relating to the distribution of the second exchange fluid in the pipes of the exchanger shown in the FIG. 1.

The exchanger shown in the FIG. 1 is essentially made of a stacking of a member of passages 1 having a rectangular section, limited by plane plates 2, 3 that separate them from groups of shapes 4 mounted in alternation with said passages.

The various passages such as 1 form together a circuit A conducting the first exchange fluid in operation, said first exchange fluid being a gas in the described particular case. As for the shapes 4, which have a square or rectangular external section, they are each provided with a longitudinal channel 5 in which is mounted a pipe 6, and the pipes 6 form a circuit B conducting the second exchange fluid in operation, said second exchange fluid being a liquid such as water in the inpoint case.

The exchanger of the FIG. 1 having a general parallelepipedic shape, the pipes of the circuit B are mounted in it in a direction perpendicular to the direction of the circulation of the gas through the circuit A (passage 1) so that the circulation 66 of the two fluids is of the crossflow type, at least locally.

The various passages of the circuit A are fed in parallel from one face of the exchanger, through a conduit B opening in a distributing dome 9. On the opposed face, the gas emerging from the various passages'is collected in a similar dome, not shown.

On both the other faces of the exchanger, the passages 1 are closed by bars 10 having a rectangular section and brazed on the separating plates. I

In every passage, a sheet 12 is mounted that describes regular corrugations between the two separating plates limiting said passage. Said sheet is also brazed on the separating plates; it acts as a spacing element between the two plates while forming a secondary exchange surface ensuring the conduction of the calories of the gas towards the separating plates and, subsequently, towards the circuit B.

Said corrugated sheets must have various shapes; the corrugations can be rounded or rectangular; they can be provided in rectangular pattern or in herring bone pattern; the sheets can be eventually apertured.

As for the circuit B for the liquid, in the particular case illustrated in the FIG. 1, the various pipes passing through the shapes 4 of a same group are connected by means of bent parts 14 mounted in succession at each of their extremities, or by means of removable collectors allowing the access to the pipes for cleaning them. Thus, the liquid circulates in series through the various pipes of a same group of shapes. On the contrary, the successive groups are fed in parallel from a common collector 15. A similar collector, on the opposed face of the exchanger, collects the liquid emerging from the last pipe of every group of shapes. If the number of going up and going down nappes of pipes 6 is sufficient from one collector to the other, the circulation can be regarded as a circulation of the countercurrent type.

The various shapes of a same group present two opposed faces in thermal contact with the passages of the circuit A. In the described particular case, said shapes 4 are brazed to the separating plates 2, 3.

Furthermore, the adjacent shapes of a same group are slightly spaced one from the other so that they limit between them parallel spaces 16 destined to collect the possible escaped fluid and to allow the detection of such leakages. Said spaces are preferably connected to an escape collecting circuit.

The elements of the circuit A: bars 10, separating plates 2, 3 and corrugated sheets 12, are made of aluminum as the shapes 4. Said various elements are brazed in a salt bath. The pipes of the circuit B are expanded on their whole length within the shapes. They are made of a cupreous alloy or of any other metal chosen with respect of the nature of the driven liquid.

The described exchanger presents therefore the advantages of the exchangers of the compact type made of brazed aluminum while allowing to use an exchange fluid incompatible with aluminum.

The heat exchange between the two fluids is made through the pipes 6 of the circuit B that conduct the calories to the shapes 4, then to the separating plates 2, 3 and to the corrugated sheets into contact with the gas. Thus, said corrugated sheets form an additional and secondary exchange surface that increases in great proportions the total exchange factor. Said secondary surface has the advantage of being easily adapted for every particular application, independently of the pipes of the circuit B, in function of the exchange conditions to be taken into account flow rates, temperatures, exchange factors and pressure-drops, particularly.

An essential advantage of the described embodiment is moreover the safety in the case in which any contact between the two fluids is dangerous. Said safety is insured by the presence of several barriers separating the two fluids one from the other. Said barriers are indeed provided at every level: the pipe of the circuit B, the shape and the plate limiting the passage of the circuit A. In order that the fluids can come into contact, it would be necessary that a leakage could occur simultaneously and at the same place through the three barriers, that is practically impossible.

Furthermore, if by exception a leakage occurs through two of these barriers, said leakage is rapidly detected in the spaces 16 between the shapes 4 and the plates 2, 3.

The described exchanger has also other advantages due in particular to the divided shape of the two circuits and to the use of brazed metal. Thus, the divided shape of the circuit A, which comprises a great number of elementary passages heated or cooled on each of their sides by two parts of the circuit B, increases the exchange performances due to the large surface of the corrugated sheets.

The use of brazed aluminum leads to a particularly compact and resisting structure and allows to prevent the strains in assembling the elements of the exchanger. The small sizes and weight of the exchanger allow to treat very important flow rates in a relatively small exchange volume. Moreover, the described exchanger is economically and reliably manufactured owing to its simple design.

The design of the exchanger according to the invention allows also to easily adapt it to any particular shape of the volume available for it. Such a possibility is illustrated by the embodiment shown in the FIG. 2.

According to the embodiment of the FIG. 2, the exchanger is limited by a cylindrical volume. However, as for the embodiment previously described, said exchanger is provided with passages 18 for the circuit of the gas, each of them containing a corrugated sheet, and with shapes 119, each of them containing a pipe 20 for the circuit of the liquid and being separated from the passages 18 by parallel plates 21. However, said plates are curved for giving them a cylindrical shape, the passages 18 being, in said case, sectors of annular crowns.

In this case, the circulation of the two fluids is of the crossflow type, the shapes 19 being in parallel with the axis of the exchanger.

On the two end faces of the cylinder, the pipes 20 are connected to collectors not shown. The gas enters the passages 18 and emerges from them through two distributing boxes 22 and 23, respectively, that are diametrally opposed in the cylindri cal exchanger.

Furthermore, the exchanger according to the invention and as described hereabove may be modified while keeping the same essential features and the same advantages without departing from the scope of the invention.

For example, if the risks of a reaction between the two exchange fluids allow to suppress one of the barriers separating the two circuits, the pipes provided in the above described embodiments can be suppressed, the liquid circulating therefore directly through the channels provided in the shapes.

In the same manner, the separating plates, designated 2 and 3 in the FIG. I and 21 in the FIG. 2, can be suppressed.

Said possibility is illustrated by the embodiment shown in the FIG. 3, wherein the particular design of the shapes allows to ensure their connection by brazing them on the side of the two adjacent passages of the circuit A, while keeping the escape collecting spaces 24.

According to another embodiment, the shapes are provided on their face into contact with the separating plates, with grooves 26 that make for an easier detection of the possible leakages at said level either through the separating plate or through the shape.

The pipes of the circuit B can have, on the other hand, any particular shape adapted to the fluid circulated and to the exchange conditions. Thus, according to the embodiment illustrated by the FIG. 4, they can contain star pattern devices 27 allowing to increase the exchange surface into contact with the liquid. They can also be provided with external grooves allowing to rapidly detect any leakage through the pipe itself, and thus to prevent the risks of corrosion of the shape; in this case, it is advantageous to mount the pipes by forcing them into the shapes, without expanding them. The grooves can be provided, not on thepipes, but on the shapes as shown in the FIG. 3 by the shape 30. Moreover, forincreasing the exchange factor, the pipes can be provided with inner spiral shaped or spring shaped disturbers.

Many other embodiments can be expected as for the circuit of the gas A. The FIG. 4 shows, by way of example, that the passages can be constituted with two corrugated sheets separated by an intermediate plate 28.

At last, one embodiment of the exchanger, for instance the exchanger on the FIG. 1, may operate by establishing the circuit B in different manner. Thus, from a mode of distribution as illustrated in the FIG. 5, wherein the pipes of a same group of shapes are connected in series and the various groups are fed in parallel, it is easy to change the connections of the pipes for obtaining the mode of distribution illustrated in the FIG. 6; in said figure, the pipes of a same group of shapes are fed in parallel, two by two.

It will be understood that the invention is not to be limited to the details given herein, but that it may be modified within the scope of the appended claims.

We claim:

1. A heat exchanger comprising a plurality of parallel passages for a gas, parallel plates forming said passages, a packing of corrugated sheet in each of said passages, and, stacked in alternation with each of said passages, groups of parallel interengaging shapes, each of said shapes having a longitudinal channel for the circulation of a liquid, two opposed faces for each of said shapes respectively adjacent to liquid to and removing liquid from said pipes.

2. A heat exchanger according to claim 1 wherein the shapes form, on their face in contact with said plates, grooves for the detection of possible leakage. 

1. A heat exchanger comprising a plurality of parallel passages for a gas, parallel plates forming said passages, a packing of corrugated sheet in each of said passages, and, stacked in alternation with each of said passages, groups of parallel interengaging shapes, each of said shapes having a longitudinal channel for the circulation of a liquid, two opposed faces for each of said shapes respectively adjacent to and engaging two successive plates disposed on each side of the corresponding group of shapes, adjacent ones of said shapes of a same group of shapes defining between them spaces for the collection and the detection of possible leakage, pipes for the liquid in the channels, means for supplying gas to and removing gas from said passages and means for supplying liquid to and removing liquid from said pipes.
 2. A heat exchanger according to claim 1 wherein the shapes form, on their face in contact with said plates, grooves for the detection of possible leakage. 